Chemistry 0620/42 February/March 2024: question paper and mark scheme

Question

Iron ore contains iron(III) oxide, Fe2O3. A blast furnace is used to extract iron from Fe2O3. Equations for some of the reactions in the blast furnace are shown. equation 1 C + O2 → CO2 equation 2 CaCO3 → CaO + CO2 equation 3 CaO + SiO2 → CaSiO3 (a) Equation 1 shows the combustion of carbon in the blast furnace. (i) Name the substance which provides the carbon for this reaction. . …… [1] (ii) State the purpose of the combustion of carbon in the blast furnace. . …… [1] (b) Iron(III) oxide, Fe2O3, in iron ore is converted to iron when it reacts with carbon monoxide, CO, in the blast furnace. (i) Calculate the percentage by mass of iron in iron(III) oxide, Fe2O3. percentage = ……% [2] (ii) State the name of the iron ore which consists mainly of iron(III) oxide. . …… [1] (iii) Describe how carbon monoxide is formed in the blast furnace. . …… [1] (iv) Write the symbol equation to show the reaction that occurs when iron(III) oxide is converted to iron in the blast furnace. . …… [2] (v) Name the chemical process which happens to iron when iron(III) oxide is converted to iron in the blast furnace. . …… [1] (c) State the type of reaction shown by equation 2. . …… [1] (d) (i) Explain why the reaction in equation 3 can be described as an acid–base reaction. . …… . …… . …… [2] (ii) State: ● the chemical name of SiO2 . …… ● the common name given to CaSiO3 when it is formed in the blast furnace. . …… [2] (e) Aluminium cannot be extracted from its ore using a blast furnace. (i) State why aluminium is not extracted from its ore using a blast furnace. . …… [1] (ii) Name the process used to extract aluminium from its ore. . …… [1] (f) Both iron(III) oxide and aluminium oxide contain metal ions with a 3+ charge. (i) Write the electronic configuration of an Al 3+ ion. . …… [1] (ii) Deduce the number of protons and electrons in an Fe3+ ion. protons electrons [2] [Total: 19]

Question

The elements in Group VII of the Periodic Table are known as the halogens. Halogens can form halide ions. (a) Identify the halogen with the lowest density at r.t.p. (room temperature and pressure). . …… [1] (b) State the appearance of bromine at r.t.p. . …… [1] (c) Use the Periodic Table to: ● give the symbol of the halogen with the highest atomic number . …… ● deduce the number of occupied electron shells in an atom of this element. . …… [2] (d) Bromine molecules have covalent bonding. (i) State what is meant by the term covalent bond. . …… . …… [2] (ii) Name one halide ion which bromine molecules can displace. . …… [1] (iii) Explain why bromine can displace the halide ion in (d)(ii). . …… [1] (e) Name a halide compound which can be used to detect the presence of water. . …… [2] (f) Calcium chloride is an ionic compound. Complete the dot-and-cross diagram in Fig. 2.1 for the ions in calcium chloride. Give the charges on each of the ions. Cl Ca Cl Fig. 2.1 [3] (g) Aqueous lead(II) ions are added to aqueous chloride ions. A white precipitate of insoluble lead(II) chloride, PbCl 2, is formed. (i) Name a lead(II) compound which can be used in this reaction. . …… [1] (ii) Write the ionic equation for this reaction. Include state symbols. . …… . …… [3] (iii) Name one other insoluble chloride. . …… [1] [Total: 18]

Question

This question is about acids, bases and alkalis. Table 3.1 shows the pH values of some substances. Table 3.1 substance pH NaOH(aq) 14 Ca(OH)2(aq) 10 H2O(l) 7 CH3COOH(aq) 4 HNO3(aq) 1 (a) Define the term base. . …… [1] (b) State what is meant by the term alkali. . …… [1] (c) Thymolphthalein is an indicator. State the colour of thymolphthalein in: ● NaOH(aq) …… ● CH3COOH(aq). …… [2] (d) (i) Use the information in Table 3.1 to identify the substance with the highest concentration of H+(aq) ions. Explain your answer. substance …… explanation …… [2] (ii) Name an indicator which can be used to identify the substance with the highest concentration of H+(aq) ions. . …… [1] (e) Complete the equation to show the dissociation of ethanoic acid, CH3COOH, in aqueous solution. CH3COOH(aq) …… [3] (f) Write the ionic equation which represents a neutralisation reaction between any acid and any alkali. . …… [1] (g) Dilute nitric acid, HNO3(aq), reacts with aqueous calcium hydroxide, Ca(OH)2(aq), as shown. 2HNO3(aq) + Ca(OH)2(aq) → Ca(NO3)2(aq) + 2H2O(l) 20.0 cm3 of 0.0150 mol / dm3 Ca(OH)2(aq) reacts with 25.0 cm3 of HNO3(aq). Calculate the concentration of HNO3(aq) in g / dm3. Use the following steps. ● Calculate the number of moles of Ca(OH)2(aq) used. …… mol ● Determine the number of moles of HNO3(aq) which react with the Ca(OH)2(aq). …… mol ● Calculate the concentration of HNO3(aq) in mol / dm3. …… mol / dm3 ● Calculate the concentration of HNO3(aq) in g / dm3. …… g / dm3 [5] [Total: 16]

Question

The equation for the reaction between methanoic acid and ethanol in the presence of a catalyst can be represented as shown. HCOOH + CH3CH2OH X + H2O ∆H = –29.5 kJ / mol X represents the ester formed. (a) (i) In the equation, methanoic acid is represented by the formula HCOOH. Name this type of formula. . …… [1] (ii) Write the empirical formula of methanoic acid. . …… [1] (b) Name and draw the displayed formula of ester X. name …… displayed formula [3] (c) The reaction is reversible and reaches an equilibrium within a closed system. (i) State what is meant by the term closed system. . …… [1] (ii) State two characteristics of an equilibrium. 1 . …… . …… 2 . …… . …… [2] (iii) Complete Table 4.1 to show the effect, if any, on the concentration of X at equilibrium for each change of condition. Table 4.1 change of condition effect on the concentration of X at equilibrium temperature is decreased concentration of HCOOH is decreased concentrations of both HCOOH and CH3CH2OH are decreased the catalyst is removed [4] [Total: 12]

Question

Butane and but-1-ene are colourless gases at room temperature and pressure. (a) Suggest why but-1-ene diffuses quicker than butane. . …… [1] (b) Identify the products formed when butane undergoes complete combustion. . …… [1] (c) One molecule of butane reacts with one molecule of chlorine in the presence of ultraviolet light. During the reaction, one hydrogen atom in butane is replaced by one chlorine atom. (i) Name the type of reaction which needs ultraviolet light. . …… [1] (ii) State the purpose of ultraviolet light during this reaction. . …… [1] (iii) Name the type of reaction which takes place when one atom of chlorine replaces one atom of hydrogen. . …… [1] (iv) Determine how many different structural isomers can form during this reaction. . …… [1] (d) When but-1-ene reacts with steam, two possible products form. (i) Identify the type of catalyst which is used in this reaction. . …… [1] (ii) Name and draw the displayed formulae of the two possible products. product 1 product 2 name …… name …… displayed formula displayed formula [4] (e) But-1-ene undergoes polymerisation. (i) State the type of polymerisation but-1-ene undergoes. . …… [1] (ii) Draw part of the polymer molecule to show three repeat units. [3] [Total: 15] The Periodic Table of Elements Group I II III IV V VI VII VIII 1 2 H He hydrogen helium Key 1 4 3 4 atomic number 5 6 7 8 9 10 Li Be atomic symbol B C N O F Ne lithium beryllium name boron carbon nitrogen oxygen fluorine neon 7 9 relative atomic mass 11 12 14 16 19 20 11 12 13 14 15 16 17 18 Na Mg Al Si P S Cl Ar sodium magnesium aluminium silicon phosphorus sulfur chlorine argon 23 24 27 28 31 32 35.5 40 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr potassium calcium scandium titanium vanadium chromium manganese iron cobalt nickel copper zinc gallium germanium arsenic selenium bromine krypton 39 40 45 48 51 52 55 56 59 59 64 65 70 73 75 79 80 84 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe rubidium strontium yttrium zirconium niobium molybdenum technetium ruthenium rhodium palladium silver cadmium indium tin antimony tellurium iodine xenon 12 85 88 89 91 93 96 – 101 103 106 108 112 115 119 122 128 127 131 55 56 57–71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 lanthanoids Cs Ba Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn caesium barium hafnium tantalum tungsten rhenium osmium iridium platinum gold mercury thallium lead bismuth polonium astatine radon 133 137 178 181 184 186 190 192 195 197 201 204 207 209 – – – 87 88 89–103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 actinoids Fr Ra Rf Db Sg Bh Hs Mt Ds Rg Cn Nh Fl Mc Lv Ts Og francium radium rutherfordium dubnium seaborgium bohrium hassium meitnerium darmstadtium roentgenium copernicium nihonium flerovium moscovium livermorium tennessine oganesson – – – – – – – – – – – – – – – – – 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 lanthanoids La Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu lanthanum cerium praseodymium neodymium promethium samarium europium gadolinium terbium dysprosium holmium erbium thulium ytterbium lutetium 139 140 141 144 – 150 152 157 159 163 165 167 169 173 175 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 actinoids Ac Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr actinium thorium protactinium uranium neptunium plutonium americium curium berkelium californium einsteinium fermium mendelevium nobelium lawrencium – 232 231 238 – – – – – – – – – – – The volume of one mole of any gas is 24 dm3 at room temperature and pressure (r.t.p.).